This Program Project focuses on the role of activins and inhibins and their membrane-bound receptors, soluble binding proteins and modulators in the regulation of reproductive function, cellular growth and development. The primary focus of this Program is to characterize the physical interactions and molecular events that lead to signal propagation by activin and inhibin. The second focus is to explore the physiologic and pathophysiologic significance of these molecules at the cellular and system levels and to study the control of protein expression and secretion as well as modes of action. The Technical Core (Core Component B) provides vital services, including protein expression, peptide synthesis, peptide/protein characterization, and generation of antibodies, needed by the Projects of this Program to carry out structural, functional and mechanistic studies. Large quantities of recombinant activin, inhibin and betaglycan fragments, essential for the structural and biological studies, will be expressed by the Core. Peptides for generation of antisera and for specific blockers of antibodies will be synthesized and purified by the Core. Synthetic peptides and recombinant proteins generated by the Core, additional recombinant proteins produced by individual Projects, and novel proteins isolated by this Program will be characterized. Posttranslational modifications of ligands and/or receptors will be identified. The analysis of polypeptides will be achieved using a number of techniques including HPLC, mass spectroscopy, NMR and automated Edman degradation. Synthetic peptides conjugated to carrier proteins will be used as immunogens to develop antibodies directed towards gene products predicted from cDNA sequences. Alternatively, proteins produced using in vitro cell expression systems will be injected directly into host animals for production of antisera. To reduce cross-reactivity with antigens other than the protein of interest, selected antisera will be immunoaffinity purified when necessary. Core B will additionally provide immunoassays of pituitary gonadotropic hormones and sex steroids for physiologic and pharmalogic studies proposed. The reagents and services provided require specialized equipment and highly trained personnel which can be most efficiently consolidated in a Core. In addition, the integrated nature of the Core assures cost efficiency, standardization of protocols and facilitates quality control.